removed theme slug from overlay attr

Author: MaggieCabrera

overlay-test/parts/header.html

@@ -16,7 +16,7 @@
 		</div>
 		<!-- /wp:group -->
 
-		<!-- wp:navigation {"overlay":"overlay-test//overlay", "layout":{"type":"flex","setCascadingProperties":true,"justifyContent":"right","orientation":"horizontal"},"style":{"spacing":{"margin":{"top":"0"}}}} /-->
+		<!-- wp:navigation {"overlay":"overlay", "layout":{"type":"flex","setCascadingProperties":true,"justifyContent":"right","orientation":"horizontal"},"style":{"spacing":{"margin":{"top":"0"}}}} /-->
 
 	</div>
 	<!-- /wp:group -->